The present invention relates to the recovery of crude oil from a formation and more particularly, to a method and system for injecting into a well any fluid which may be useful in improving the production of a well and/or in maintaining the production equipment. The method and system of the present invention permits injection of the fluid in an optimal amount for facilitating extraction of the crude oil from the well.
Within the existing state of the art, fluids are injected into production wells in a number of different ways. For example, as shown in FIG. 1, fluids for diluting oil being extracted have been injected through the annular space that exists between the well casing and the production tube. The diluting fluid and the crude oil are permitted to mix in an area below the inlet of the pump. This procedure has been found to be unsatisfactory because the injection pressure of the diluting fluid, together with the hydrostatic column of fluid in the annular space, interfere with the production pressure of the oil deposit and reduce the efficiency of the production equipment.
It is also known in the art, as shown in FIG. 2, to inject a fluid into a well through the production pipe. In this arrangement, mixing of the crude and the fluid usually occurs within a perforated nipple located some fifty feet above the production pump. The fluid/oil mixture is permitted to flow to the surface via perforations in the nipple and the annular space between the well casing and the production pipe. There are several disadvantages associated with this technique. First, if a diluting fluid is injected into the well in this way, it does not pass through the production pump. As a result, the high viscosity of the crude oil can cause deterioration of the pump components and ultimate failure of the pump. Second, this arrangement could not be used to inject a maintenance fluid such as an anticorrosive fluid or an oxide inhibitor into the production equipment because again it would not pass through the production pump. Another disadvantage of these techniques is their inability to deliver an assisting fluid in the precise optimal proportions needed to facilitate the extraction process.